The beet armyworm, Spodoptera exigua, is one of the worldwide distributed agricultural pest insects and has been known to show high resistance to conventional chemical insecticides. Since it has been reported that secondary metabolites from actinomycetes show insecticidal activities against various insect pests, actinomycetes could be a potential source of insecticidal compounds. In this study, culture extracts of Streptomyces strains were tested for their insecticidal activity against Spodoptera exigua. Among them, culture extracts of IMBL-0003 strain which was identified as Streptomyces celluloflavus showed a high insecticidal activity (more than 90% mortality). These results suggested that secondary metabolites of this isolate could have potentials to be a efficient eco-friendly pesticide for controling Spodoptera exigua.

The development of entomopathogenic fungi has received increasing interest as part of integrated pest management strategies as biocontrol agents. It is reasonable to assume that entomopathogenic fungi might produce secondary metabolites modulating juvenile hormone for their survival against defense mechanisms of host insects. In this study, acetone extracts of 189 entomopathogenic fungi cultured on unpolished rice medium were screened for their juvenile hormone antagonist (JHAN) activities using the yeast-two hybrid system. Among 14 extracts showing JHAN activities, extract of the F-145 showed high level of insecticidal activities against both Plutella xylostella and Aedes albopictus. This isolate was identified as Lecanicillium attenuatum. These results suggested that the Lecanicillium attenuatum could be useful for development of eco-friendly insecticides.

Entomopathogenic fungi have been widely studied for their potential as the effective biological control agents. Theyproduce variety of secondary metabolites with insecticidal activities, and it is reasonable to assume that entomopathogenicfungi might produce secondary metabolites modulating juvenile hormone for their survival against defense mechanismsof host insect. In this study, Acetone extracts of 189 entomopathogenic fungi cultured on unpolished rice medium werescreened for their juvenile hormone antagonist (JHAN) activities using the yeast-two hybrid system. Among them, 14extracts showed high level of JHAN activities and their insecticidal activities against Aedes albopictus were investigated.

Secondary metabolites isolated from Actinomycete have been studied to find potent pest control agents as their insecticidal and growth inhibitory activities. In order to investigate novel insecticidal compounds, second metabolites from 363 Actinomycete isolates were evaluated for their insect growth regulatory activities. Among them, ethyl acetate extracts from ten Streptomyces spp. showed high level of Juvenile hormone antagonist activity. In addition, their insecticidal activities were tested against larvae of Aedes albopictus, Plutella xylostella and Laodelphax striatellus. These results suggested that secondary metabolites from Streptomyces spp. could be used for development of novel IGR-based insecticides.

Entomopathogenic fungi have been widely studied for their potential as the effective biological control agents. They produce variety of secondary metabolites with insecticidal activities, and it is reasonable to assume that entomopathogenic fungi might produce secondary metabolites modulating juvenile hormone for their survival against defense mechanisms of host insect. In this study, acetone extract of the Lecanicillium spp. cultured on unpolished rice medium showed juvenile hormone antagonist (JHAN) activity in the yeast-two hybrid β-galactosidase assay and high insecticidal activity against Aedes albopictus and Plutella xylostella. In addition, to compare bioactivities of secondary metabolites from solid and liquid culture, the Lecaniciilium spp. strain cultured on unpolished rice medium or PDB medium were serially extracted with acetone and ethyl acetate respectively. Both extracts showed JHAN activity and high insecticidal activity against A.albopictus. Theses results suggested that secondary metabolites of entomopathogenic fungi could be useful for development of novel IGR insecticides.

Entomopathogenic fungi have been widely studied for their potential as the effective biological control agents. They produce variety of secondary metabolites with insecticidal activities, and it is reasonable to assume that entomopathogenic fungi might produce secondary metabolites modulating juvenile hormone for their survival against defense mechanisms of host insect. In this study, Beauveria spp. and Lecanicillium spp. strains cultured on unpolished rice medium were extracted with acetone. Both extracts showed juvenile hormone antagonist (JHAN) activities in the yeast-two hybrid β-galactosidase assay. In addition, they showed high insecticidal activities against Aedes albopictus, Plutella xylostella, and Ostrinia furnacalis. These results suggested that secondary metabolites of entomopathogenic fungi could be useful for development of novel IGR insecticides.

Streptomyces is the largest genus of Actinobacteria that forms fungus-like branched networks of hyphae. Streptomyces has been clinically important because they produce various secondary metabolites with antibacterial, antifungal, and nematocidal activities. In order to explore novel insecticidal compounds, extracts from 363 strains of Actinobacteria were screened for their juvenoid and anti-juvenoid activities using yeast-two hybrid system. Among them, extract of Streptomyces spp. showed high anti-juvenoid activity. This extract also showed high level of insecticidal activities against larvae of Aedes albopictus, Laodelphax striatellus, and Ostrinia furnacalis. These results suggested that the secondary metabolites of Streptomyces could be natural sources of novel insecticidal compounds.

This study tested a hypothesis that the bacterial immunosuppresants enhance BtI susceptibility of two mosquitoes, the forest mosquito (Aedes albopictus) and the house mosquito (Culex pipiens pallens). Three symbiotic bacteria Xenorhabdus nematophila (Xn), X. hominickii (Xh), and Photorhabdus temperata subsp. temperata (Ptt) were isolated from their symbiotic nematodes and cultured in nutrient broth to allow them to produce the secondary metabolites. BtI gave significant toxicities to A. albopictus and C. pipiens pallens larvae: 50% of lethal concentration to be 2.9 × 105 spores/mL and 2.2 × 105 spores/mL at 16 h after treatment, respectively. Addition of each bacteria-cultured broth significantly enhanced BtI toxicity to the mosquito larvae by lowering LC50 values of BtI to A. albopictus larvae (1.5 × 105 to Xn, 1.7 × 105 to Xh, and 1.9 × 105 to Ptt, respectively) and to C. pipiens pallens larvae (1.2 × 105 to Xn, 1.3 × 105 to Xh, and 1.5 × 105 to Ptt, respectively). Based on these results, we developed a new mosquitocidal Bt formulation called ‘Dip-Kill’, which consisted of 80% Xn-cultured broth, 10% BtI (1010 spores/mL), and 10% preservative. Only 400 ppm of Dip-Kill showed 100% mortality to fourth instar larvae of A. albopictus and C. pipiens pallens 16 h after treatment.

Ingestion of plant secondary metabolites (PSMs) presents a major challenge to mammalian herbivores. We investigated the relationship between PSM concentrations in the diet and feeding patterns in sheep fed diet containing flavone extracted from Apocynum venetum. Results showed that the flavone concentrations significantly influenced food intake by sheep. With the concentration of flavone in diet increase, sheep can regulate their intake of PSM within limits that are tolerable.

식물의 이차 대사산물은 다양한 생물활성을 가지며 자외선은 이차 대사산물의 생성에 영향을 미치는 것으로 알려져 있다. 뽕나무는 다양한 종류의 유용 성분을 함유하여 활용가치가 높은 식물 중의 하나이다. 본 연구에서는, UV 조사에 따른 뽕나무 잎의 이차 대사산물의 변화를 조사하기 위하여, 뽕나무 잎을 LC-MS를 이용하여 무표적 분석법으로 분석하였으며, 무표적 분석으로 얻은 scan data를 bioinformatics 프로그램인 R의 XCMS package를 이용하여 profiling 한 결과, 적어도 35종 이상의 화합물에서 UV-C 조사에 따른 양적인 변화가 발견되었다. 이들 중 14종의 화합물은 분리 및 NMR spectrum 비교 또는 표적 분석을 통하여 종류를 확인하였으며, 종류가 확인된 성분에 대해 정량분석을 수행한 결과, morin(464배), oxyresveratrol(256배), 2,3-trans-dihydromorin(170배), 2",4",2,4-tetrahydroxychalcone(120배), catechin(84배), 4"-prenyloxyresveratrol(43배), moracin M(35배) 등의 함량이 현저하게 증가한 것으로 나타났다. 또한 UV-C를 조사한 뽕나무 잎은 대조구에 비하여 항산화 활성이 2.1-2.4배, tyrosinase 억제 활성이 2.3배 증가한 것으로 조사되었다. 이러한 조사 결과는 자외선의 조사가 뽕나무 잎의 기능성을 향상시켜 기능성 식품, 약용 또는 화장품 소재로서의 활용 가치를 향상시키는 유용한 수단이 될 수 있음을 보인다.

Background : Pachyrhizus erosus (Leguminosae), locally called as “Yam bean” is a traditional medical plant that grows in the tropical and subtropical region. The root of P. erosus is used by the local people to treat insomania, treatment of osteoporosis and extracts of this plant have shown antioxidant activity, immunomodulatory activity, tyrosinase inhibitionby, antitumour properties and cardiovascular benefit. Methods and Results : Free radical scavenging activity was evaluated using α-tocopherol and butylated hydroxy toluene (BHT) as standard antioxidants. The radical scavenging activity was measured using the stable radical 1,1-diphenyl–2-picrylhydrazyl (DPPH) and ABTS assay. Total phenolic content was determined by following Folin-Ciocalteau colorimetric method and Total flavonoids were determined using aluminium chloride calorimetric methods. Phenolic compound concentration and compositions were determined by HPLC-MS/MS system. Seedlings grown under the flourescent light (Fl) exhibited the highest DPPH radical scavenging activity when compared to the plants treated with light emitting diodes (LEDs) and light emitting plasma (LEP). LED-Blue showed the higher DPPH radical scavenging activity and ABTS concentration of PE compared to other LEDs. The accumulation of phenolic compounds increased under different white-LEDs conditions as compared to LEP and FL light conditions. Conclusion : In this study, antioxidant activity and phenolic compound composition of P. erosus was improved by the application of LED and LEP.

콜라비의 저장기간 동안 품질이 유지되는 적정 유통기간 설정을 위해, 2차대사산물 및 생리적 변화를 조사하였다. 그 결과, 콜라비를 상온에 저장할 경우, 저장 2주후부터 부패가 발생하기 시작함과 더불어 총 페놀 및 플라보노이드 함량 또한 급격한 감소를 보였다. 반면에 저온저장의 경우, 저장 2개월간 품질의 변화가 거의 없고 기능성 성분도 초기값을 유지하거나 높은 값을 유지하였다. 콜라비의 총 페놀 함량과 플라보노이드 함량은 저온저장으로 증가하였고, 상온저장 기간 동안 감소하였다. 또한 포장처리에 관하여, 콜라비의 페놀함량은 저장기간동안 포장처리 유무에 따른 유의적인 차이가 없었으나, 플라보노이드 함량은 0.05 mm PE 필름 밀봉시 이들 성분의 변화가 적은 것으로 나타나, 콜라비를 포장하여 저장하는 것이 플라보이드 함량 보존에 유효한 것으로 나타났다. 항암 성분으로 알려진 glucosinolate는 저장 기간 동안 유의적인 차이가 없는 것으로 나타나, 콜라비가 장기 저온저장동안 이들 유용한 성분을 유지하는 것으로 보인다. 본 연구에서 콜라비의 저장기간 동안 2차대사산물과 외관 품질변화는 밀접한 상관관계가 나타났다. 이러한 결과로부터, 페놀화합물과 같은 2차대사물질이 콜라비의 저장수명 구명을 위한 품질 지표로서 검토될 수 있을 것으로 제시한다.